CN112250425A

CN112250425A - Production method of brown corundum

Info

Publication number: CN112250425A
Application number: CN202011091413.7A
Authority: CN
Inventors: 宋保峰; 田守信; 宋保国; 刘传省
Original assignee: Chiping Haoxin Industrial Co ltd
Current assignee: Chiping Haoxin Industrial Co ltd; YANGGU XINMIN REFRACTORY MATERIALS CO Ltd
Priority date: 2020-10-13
Filing date: 2020-10-13
Publication date: 2021-01-22
Anticipated expiration: 2040-10-13
Also published as: CN112250425B

Abstract

The invention belongs to the technical field of corundum processing and application, relates to brown corundum, and particularly relates to a production method of brown corundum. The method comprises the following effective steps: firstly, dividing aluminum slag ash serving as a raw material into two batches, wherein scrap iron is added in the second batch; adding a first batch of aluminum slag ash raw material into an electric furnace, and heating and melting in an oxidizing atmosphere; after the melting is finished, adding a second batch of materials, heating and melting, gasifying and reacting in a reducing atmosphere; and after the reaction is completed, oxidizing and refining the obtained blank, and finally discharging to obtain the brown corundum. The invention provides a production method of brown corundum, which not only solves the industrial waste such as aluminum slag ash, but also reduces the use of electric energy by effectively improving the existing production method, thereby achieving the purposes of energy conservation and environmental protection.

Description

Production method of brown corundum

Technical Field

The invention belongs to the technical field of corundum processing and application, relates to brown corundum, and particularly relates to a production method of brown corundum.

Background

Corundum is an artificial material refined from bauxite as a main raw material through a mining furnace, and can be used as an abrasive and a refractory material. The high-purity corundum is white corundum, and the brown corundum contains a small amount of impurities. Currently, brown fused alumina smelting is to take special-grade alumina clinker as a main raw material, add a small amount of iron and carbon, add the mixture into an electric furnace, heat the mixture until the raw material is melted, and complete a series of reactions:

TiO₂+2C+Fe＝Ti-Fe+2CO (1)

SiO₂+Fe+2C＝Si-Fe+2CO (2)

Fe₂O₃+3C＝2Fe+3CO (3)

R₂O+C＝2R+CO (4)

through the above reaction, the impurities are reacted to generate gas (alkali metal) and the silicon-iron-titanium alloy with high specific gravity is discharged and deposited on the bottom of the furnace. The melt at the upper part of the molten pool is a material with high alumina content, and the brown corundum is obtained by pouring, cooling and crushing. Can be used for manufacturing grinding tools and grinding materials, and also can be used for manufacturing high-grade refractory materials and the like. The power consumption of the brown corundum smelted by the pouring method is 2540kwh/t, and the power consumption of the brown corundum smelted by the fixing method is 2820 kwh/t. The furnace condition is unstable, and the cost is increased because the calcined alumina is required. The brown corundum production is divided into four stages of arc striking, smelting, controlling and refining. Long time period, large power consumption and high raw material cost.

At present, white corundum and compact corundum are smelted by taking industrial alumina as a main raw material, adding the industrial alumina into an electric furnace, and heating until the raw material is melted and certain impurities are volatilized to obtain a product.

In order to reduce the cost, the patent of producing brown corundum by using aluminum slag ash as a main raw material has appeared in recent years. In fact, white corundum and compact corundum can be completely obtained as long as the control is good and the subsequent reaction and refining are well controlled. Typical patents for producing brown fused alumina are: CN200610148219.1 uses aluminum ash to replace a certain amount of bauxite to produce brown corundum, and adds reducing agent coke powder and precipitator iron filings, and mixes them uniformly, adds them into electric arc furnace, and makes them undergo the processes of smelting, pouring out, cooling, breaking, pulverizing and sorting. Thus reducing the cost of producing the brown corundum by 5 to 25 percent. The resource is recycled. However, the patent does not have a specific smelting process, and qualified brown corundum is difficult to produce. In particular, the addition of coke powder results in the occurrence of:

Al₂O₃+3C＝Al₂OC+2CO (5)

2Al2O₃+9C＝Al₄C₃+6CO (6)

2Al₂O₃+3C＝Al₄O₄C+2CO (7)

the generated Al2OC, Al4C3 and Al4O4C are easy to generate hydration reaction with moisture in humid air:

Al₂OC+5H₂O＝2Al(OH)₃+CH₄↑ (8)

Al₄C₃+12H₂O＝4Al(OH)3+3CH₄↑ (9)

Al₄O₄C+8H₂O＝4Al(OH)₃+CH₄↑ (10)

this is a very voluminous expansion reaction and generates gases, which lead to pulverization and rejection of the brown fused alumina and even failure of the finished product. Therefore, the patent is difficult to implement and ensure the product quality. The patent CN 201310205936.3 firstly adds aluminum ash into hot water, then sends the hot water into a plastic container communicated with the outside for reaction for a period of time, then discharges the hot water in the plastic container, adds hot water with the same weight as the discharged water, stands for a period of time, then separates out the aluminum ash, rinses the aluminum ash with water, then uses a vacuum filter to filter and dries the obtained aluminum ash, and adds iron filings into the dried aluminum ash to smelt under the condition of temperature of 1700 plus 1800 ℃ to obtain the product. According to the invention, after the aluminum ash is treated by a certain method, part of soluble impurities are removed, the content of aluminum oxide is increased, but the heat generated by the aluminum and AlN changed into aluminum oxide is wasted, and the generated hydrogen and ammonia cause environmental pollution and bring safety problems. Even if treated, increases the investment. This significantly increases the cost. The patent CN201611069675. X and CN 201611069568.4 do not fully utilize energy, and the acidification and the alkalization treatment bring environmental problems such as sewage. Which leads to increased complexity and cost of production.

Disclosure of Invention

Aiming at the technical problems existing in the preparation of the brown corundum, the invention provides the production method of the brown corundum, which has the advantages of reasonable design, simple and convenient method, low production cost, energy conservation and environmental protection.

In order to achieve the purpose, the invention adopts the technical scheme that the invention provides a production method of brown corundum, which comprises the following effective steps:

a. firstly, dividing aluminum slag ash serving as a raw material into two batches, wherein scrap iron is added in the second batch;

b. adding a first batch of aluminum slag ash raw material into an electric furnace, and heating and melting in an oxidizing atmosphere;

c. after melting, adding a second batch, heating and melting, gasifying and reacting under a reducing atmosphere

d. And after the reaction is completed, oxidizing and refining the obtained blank, and finally discharging to obtain the brown corundum.

Preferably, in the step a, the aluminum slag ash refers to aluminum slag ash generated in the processes of electrolytic aluminum, molten aluminum and refined aluminum, wherein Al is less than or equal to 30 percent, and AlN is less than or equal to 45 percent

Preferably, in the step a, the proportion of the second batch is determined according to the contents of Al and AlN in the two batches of raw materials and the total contents of TiO2 and SiO2 in the two batches of raw materials, and the TiO2 and the SiO2 are completely reduced by Al and AlN.

Preferably, in the step b, the oxidizing atmosphere is air or oxygen gas introduced into the electric furnace, the amount of the introduced gas is adjusted according to the amount of O2 required for oxidizing Al and AlN in the aluminum slag ash, and the coefficient of introduction is generally 1.05 to 1.2.

Preferably, in the step a, the iron filings are added in an amount which is 40% of the total amount of the metal iron ≧ SiO 2.

Preferably, in the step d, the oxygen blowing amount and time of the oxidation refining are based on no carbon in the melt, namely, the carbon content is less than or equal to 0.15 percent.

Compared with the prior art, the invention has the advantages and positive effects that,

1. the invention provides a production method of brown corundum, which not only solves the industrial waste such as aluminum slag ash, but also reduces the use of electric energy by effectively improving the existing production method, thereby achieving the purposes of energy conservation and environmental protection.

Detailed Description

In order that the above objects, features and advantages of the present invention can be more clearly understood, the present invention will be further described with reference to the following examples. It should be noted that the embodiments and features of the embodiments of the present application may be combined with each other without conflict.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, however, the present invention may be practiced in other ways than those specifically described herein, and therefore the present invention is not limited to the specific embodiments of the present disclosure.

The aluminum slag ash generated in the production process of electrolytic aluminum and secondary aluminum is used as a main raw material, and the raw materials are cheap and are even industrial waste materials which are equivalent to resource regeneration and high added value. These raw materials are charged into an electric arc furnace in a first batch and are subjected to electric melting heating. During the heating process, oxygen or air is blown simultaneously to raise the temperature until the melting is carried out. In the heating process, low boiling point substances or impurities such as cryolite, chloride and the like exist in the raw materials, and the raw materials are changed into gas at high temperature to be discharged. These gases can be collected by dust removal. These fluoride and chloride properties are shown in the following table:

TABLE 1 fluoride and chloride Performance Table

As can be seen from the above table, the fluorides and chlorides contained in the selected raw materials for electric smelting are easily turned into gases to be discharged, which is equivalent to purifying the raw materials. During the heating, the following oxidation reactions also take place inside the furnace:

4AlN+3O₂＝2Al₂O₃+2N₂↑ (11)

4Al+3O₂＝2Al₂O₃ (12)

these two reactions are exothermic, the former giving an exotherm of 12.66KJ/g.aln, and the latter 31 KJ/g.al. The heating speed is accelerated, the electricity is saved, meanwhile, alumina is generated after oxidation, and the purity of the raw material is improved. When the melting and oxidation are completed, the oxygen blowing or air blowing is stopped. A second batch of material was added, the second batch being a mixture of iron filings and a portion of the aluminum dross. And (4) adding the mixture into the furnace, standing the gas in the furnace, and electrifying for smelting to form reducing atmosphere for smelting. The smelting thus takes place with the following redox reactions:

Fe₂O₃+2Al＝2Fe↓+Al₂O₃ (13)

3SiO₂+4Al+3Fe＝3Fe-Si↓+2Al₂O₃ (14)

3TiO₂+4Al+3Fe＝3Ti-Fe↓+2Al₂O₃， (15)

3SiO₂+4AlN+3Fe＝3Fe-Si↓+2Al₂O₃+2N₂↑ (16)

3TiO₂+4AlN+3Fe＝3Fe-Ti↓+2Al₂O₃+2N₂↑ (17)

3R₂O+2Al＝6R↑+Al₂O₃ (18)

3R₂O+2AlN＝6R↑+Al₂O₃+2N₂↑ (19)

the oxidation-reduction reaction produces Si, Ti, and Fe which are alloyed. They are higher in density than corundum and do not co-fuse with corundum, so that the Si-Fe-Ti alloy precipitates on the bottom of the furnace, the upper melt being alumina (corundum). After the reaction is completed, SiO is oxidized and reduced by oxidation-reduction reaction₂、TiO₂And Fe₂O₃The purity of the corundum liquid is obviously improved after the corundum liquid is removed. It is to be noted that the atmosphere in the furnace is static, since there is no evacuation. The fluoride and chloride carried in by the second batch have not run out, and also during the supply of electricity, the electrode supplies carbon and the reactions (5) to (7) with alumina take place at high temperatures. Formed Al₂OC、Al₄C₃、 Al₄O₄All C are easy to generate hydration reactions (8) - (10) with moisture in humid air. Resulting in product instability and chalking. Therefore, before discharging, it is necessary toThe Al content of the melt is required to be regulated₂OC、Al₄C₃、Al₄O₄C is removed. Namely, oxygen or air is blown to cause the following reaction to occur:

Al₂OC+2O₂＝Al₂O₃+CO₂ (20)

Al₄C₃+6O₂＝2Al₂O₃+3CO₂ (21)

Al₄O₄C+2O₂＝2Al₂O₃+CO₂ (22)

CO₂discharging, eliminating aluminum carbide and aluminum oxycarbide, converting into aluminum oxide, improving the stability of the fused corundum on one hand, and improving the purity and yield of the fused corundum on the other hand. In the processes of oxygen blowing and air extraction, chloride and fluoride in the second batch of the added raw materials are also extracted, so that the purity is further improved. And pouring out the melt in the furnace and cooling to obtain the corundum. According to the density and purity, the corundum is divided into brown corundum, white corundum and compact corundum. Can be used as refractory material and abrasive tool. The ascending gas is cooled and dedusted to obtain fluorides and chlorides, and the dedusted powder can be used as a refining agent for producing magnesium metal and a flux of aluminum oxide for electrolytic aluminum. The ferrosilicon-titanium alloy precipitated at the furnace bottom can be used as a deoxidizer for ferrous metallurgy and a refractory material counterweight material.

Here, it should be noted that: the first batch and the second batch are added according to the SiO in the raw materials₂、 TiO₂、Fe₂O₃、R₂The O content and AlN and Al contents in the second batch were calculated in accordance with the complete reactions of (13) to (19).

It is worth noting that if a catalyst containing Al: 18% of AlN 7%, thus theoretically saving electricity by smelting one ton of corundum due to the exothermic oxidation of aluminum and aluminum nitride: 12.66 × 1 × 7% × 109+31 × 18% × 1 × 109/3600000 ═ 1796 kwh/t. Therefore, less electricity is required to produce corundum from aluminum dross. This results in a great cost reduction. Therefore, the development of the aluminum slag ash as the raw material for producing corundum is very promising.

Example 1, 1000kg of aluminum slag ash for aluminum refining is taken, and the aluminum slag ash comprises the following chemical components: al (Al)₂O₃:60％， AlN:5％，Al:18％，MgCl₂:4％，NaCl:4％，SiO₂:7％.TiO₂:1％， Fe₂O₃0.5 percent. Putting the mixture into an electric arc furnace, heating to raise the temperature, starting oxygen blowing when the temperature reaches 800 ℃, and simultaneously starting air draft dust removal equipment. When the materials are completely melted, stopping oxygen blowing and reducing air draft equipment, adding 411kg of aluminum slag ash and simultaneously adding 10kg of scrap iron. And carrying out arc heating and melting. After the materials are completely melted, the air draft is increased for dedusting and the oxygen blowing refining is carried out for 15 minutes, the temperature reaches 2200 ℃, and the materials are discharged after the standing for 2 minutes. Then cooling to normal temperature, crushing and processing into different granular materials. Obtaining a silicon-iron-titanium alloy bottom material: 40kg, 90kg of dust removal powder and 1320kg of corundum material, and the product has the following properties: al (Al)₂O₃:98.5％，SiO₂0.3 percent, and the particle density is 3.78g/cm³The apparent porosity was 2%. Meanwhile, the power consumption is 900kwh, which is about 682kwh/t of the corundum product.

Example 1, 5300kg of aluminum slag ash for aluminum refining is taken, and the chemical components of the aluminum slag ash are as follows: al (Al)₂O₃:52％， AlN:7％，Al:25％，AlF₃:6％，NaF:4％，SiO₂:5％.TiO₂:0.5％， Fe₂O₃0.5 percent. And (3) placing the powder into an electric arc furnace, heating to raise the temperature, starting to blow air when the temperature reaches 800 ℃, and simultaneously starting an air draft dust removal device. And after the materials are completely melted, stopping blowing air and lowering the air suction equipment, and adding 700kg of aluminum slag ash and 90kg of scrap iron. And carrying out arc heating and melting. After the materials are completely melted, the air draft is increased for dedusting and the oxygen blowing refining is carried out for 15 minutes, the temperature reaches 2200 ℃, and the materials are discharged after the standing for 2 minutes. And then cooling to normal temperature, and crushing and processing into different granular materials. Obtaining a silicon-iron-titanium alloy bottom material: 272kg, 700kg of dust removal powder and 5010kg of corundum material, and the product has the following properties: al (Al)₂O₃:97.2％，SiO₂0.4 percent, and the particle density is 3.81g/cm³The apparent porosity was 1.2%. Meanwhile, the power consumption is 2905kwh, which is about 580kwh/t of corundum products. Compared with the power consumption of 1400kwh/t of the traditional white corundum, the power is saved by 50 percentThe above. Compared with the power consumption of 2500kwh/t of brown corundum, the power is saved by more than 70%. Has great energy-saving and environment-friendly value, and the effects of reducing cost and improving efficiency.

The above description is only a preferred embodiment of the present invention, and not intended to limit the present invention in other forms, and any person skilled in the art may apply the above modifications or changes to the equivalent embodiments with equivalent changes, without departing from the technical spirit of the present invention, and any simple modification, equivalent change and change made to the above embodiments according to the technical spirit of the present invention still belong to the protection scope of the technical spirit of the present invention.

Claims

1. The production method of brown corundum is characterized by comprising the following effective steps:

c. after the melting is finished, adding a second batch of materials, heating and melting, gasifying and reacting in a reducing atmosphere;

2. The method for producing brown fused alumina according to claim 1, wherein in the step a, the aluminum slag ash refers to aluminum slag ash generated in electrolytic aluminum, molten aluminum and refined aluminum processes, and Al is less than or equal to 30 percent and AlN is less than or equal to 45 percent.

3. A method according to claim 2, wherein in step a, the proportion of the second batch is determined according to the Al and AlN contents of the two batches and the total TiO content of the two batches₂、SiO₂In order to determine the content, TiO should be used₂And SiO₂Completely reduced by Al and AlN.

4. The method for producing brown fused alumina according to claim 3, wherein in the step b, the oxidizing atmosphere is air or oxygen which is introduced into the electric furnace in an amount according to the oxidation requirement of Al and AlN in the aluminum slag ash₂The amount is adjusted, and the ventilation coefficient is generally 1.05-1.2.

5. The method for producing brown fused alumina according to claim 4, wherein in the step a, the iron filings are added in an amount which satisfies that the metallic iron is more than or equal to SiO₂40% of the total amount.

6. A method for producing brown corundum according to claim 5, characterized in that in the step d, the oxygen blowing amount and time for the oxidation refining are based on no carbon in the melt, i.e. the carbon content is less than or equal to 0.15%.